Sierra Top-Trak 820 Series, Инструкция по эксплуатации, Страница: 36 / 45

Series 820 Instruction Manual Appendix A
IM-82-C A-3
Where:
H = The constant amount of heat applied to the sensor tube,
m = The mass flow rate of the gas (gm/min)
¥
C
r
= The coefficient of specific heat of the gas (Cal/gm);
C
r
is given in the Table (at 0
°
C),
D
T = The temperature difference between the downstream and
upstream coils, and
N = A correction factor for the molecular structure of the gas
given by the following table:
Number of Atoms in the Gas Molecule N
Monatomic 1.040
Diatomic 1.000
Triatomic 0.941
Polyatomic 0.880
The mass flow rate, m, can also be written as:
¥
m = Q
¥
r
(3)
Where:
r
= The gas mass density at standard conditions (g/l);
r
is given
in the tables (at 0
°
C, 760 mm Hg).
Furthermore, the temperature difference,
D
T, is proportional to the
output voltage, E, of the mass flow meter, or
D
T = aE (4)
where:
a = A constant.
If we combine equations (3) and (4), insert them into equation (2),
and solve for Q, we get
Q = (bN/
r
C
p
) (5)
where:
b = H/aE = a constant if the output voltage is constant.